1. Field of the Invention
The present invention relates to a thermoplastic resin composition. More particularly, it relates to a thermoplastic resin composition having a high heat resistance and an excellent impact resistance. The thermoplastic resin composition of the present invention can be advantageously used for the production of automobile parts such as interior parts, for example, a meter hood, a meter cluster, an instrument panel and a console box, exterior parts, for example, a bumper, an outer plate material and a lamp housing, and various machine parts.
2. Description of the Related Art
A polyester resin such as polyethylene terephthalate or polytetramethylene terephthalate is now often used as an engineering plastic for articles to be used at high temperatures, for example, an openable tray, an exterior part of a thermal implement and an electrical part, wherein the high melting point of the resin is utilized. Since the polyester resin has a poor strength and toughness, a method of incorporating a methyl methacrylate/butadiene/styrene copolymer (MBS resin) comprising a butadiene polymer as the rubber component into the polyester resin for improving the impact resistance has been proposed.
A polycarbonate resin has an excellent impact resistance, heat resistance, dimensional stability, and electrically insulating properties, and is widely used for the production of machine parts, protective safety tools, electrically insulating articles, optical machine parts, containers and the like.
The polycarbonate resin has a poor flowability and chemical resistance, and as the means for eliminating this defect, a polymer alloy formed by incorporating a saturated polyester resin such as polyethylene terephthalate or polytetramethylene terephthalate into the polycarbonate resin has now been proposed (Japanese Examined Patent Publication No. 36-14035, Japanese Examined Patent Publication No. 53-12537 and Japanese Examined Patent Publication No. 57-2744), and the application fields of this polymer alloy have been expanded. Nevertheless, if the saturated polyester resin is incorporated into the polycarbonate resin, the strength and toughness inherently possessed by the polycarbonate resin are lost, and therefore a method of improving the impact resistance by further incorporating an MBS resin has been proposed (Japanese Examined Patent Publication No. 55-9435).
As seen from the foregoing description, it is known that an MBS resin is incorporated in a thermoplastic resin such as a saturated polyester resin or a polycarbonate resin for improving the impact resistance, and it is known also that the MBS resin is incorporated in a vinyl chloride resin.
The improvement by incorporation of the MBS resin, however, does not result in a satisfactory increase of the impact resistance, and a further improvement is now desired.